The manufacture of golf balls typically involves a series of sequential processes performed at different processing stations, typically spatially separated one from another. For example, golf balls typically have a core and a dimpled cover formed thereover.
The golf ball cover typically contains a white or other colored concentrate, or is painted. Further, indicia (such as a ball number, a ball brand name, and/or a company name) can be applied to the surface, such as by pad-printing, thereon. A clear protective coat is commonly applied over the production print to enhance the appearance of the finished golf ball (such as by providing a shiny exterior) and to improve durability. A prime coat, typically a film about one-half the thickness of the clear coat, may be applied before production printing or over the production print and before the application of the clear coat. The prime coat prevents running or smearing of typical ink indicia.
Typically, golf balls which have just been covered with a clear coat are transported from a clear coat spray paint booth to a separate drying station at a remote location. Additional printing, such as a logo, may be applied over the cured clear coat.
Each process must be carefully monitored for quality assurance purposes. Inspections are typically performed for assuring a desired confidence level in production quality. Quality control criteria, may be in place as well. The manufacturer may further choose to manually inspect the entire lot being inspected if a given number of defective balls are found therein. Moreover, if a major defect, such as a gross cosmetic defect or a defect affecting performance or durability, is found the manufacturer may choose to shut down the entire system.
There has been a continuing desire to achieve high production rates. Because automated apparatuses typically may function faster than human operators, there has been an ongoing goal to reduce, if not eliminate, human intervention during the manufacturing process. Thus, each of the above processes is typically performed at a separate automated processing station functioning at optimal efficiency and speed so that the overall production rate is maintained at the desired high level. For instance, pad-printing apparatus preferably includes an array of print-pads arranged to apply a production print sequentially on various locations on the surface of the golf ball, the golf ball being indexed before being passed to the next print-pad.
The clear coating process preferably is performed by an automated spray painting technique utilizing a spray paint booth with one or more spray paint guns. A quick drying clear coat paint having a catalyzing agent (such as a solvent that dissipates quickly to dry the clear coat) may be used to reduce the usual clear coat drying time of about ten hours to about one and one-half hours.
Automation of the manufacturing process gives rise to various types of manufacturing defects. For example, automated pad-printing equipment may create smudges from excess ink carried by the printing pad. Other production print defects occur, as well. Vibration or improper set-up, such as improper positioning or accidental switching of the paint supply hoses (resulting in cut-off of paint supply to the respective spray guns), of the spray gun of an automated paint spray booth results in defectively coated golf balls. Moreover, the clear coat paint may periodically clog the spray booth filter, interfering with proper spraying of paint therefrom to coat the golf ball. As long as the improper functioning of the processing station continues, an increasingly larger number of improperly treated golf balls are produced.
One particular instance in which inspection of the results of a process shortly after completion is important is in the clear coat spray painting operation. Clear coated golf balls have been transported on a tray, via a material handling truck, from the clear coat station to a drying room to be cured for approximately ten hours. A recent improvement in the clear coat application process is the use of a fast-drying clear coat which hardens quickly (approximately one and one-half hours). However, catalyzation may occur even in the spray paint booth, resulting in a thick brittle coating on the spray booth filter and increasing the probability of spray paint operation malfunctions. Such malfunctions as clogging of spray guns and gelling of the clear coat during use result in inadequate clear coating of the golf ball. Moreover, transfer of the freshly coated golf ball into the curing station before inspection does not alert the operator to attend to unacceptable spray painting apparatus conditions until nearly two hours later. Thus, ever increasing production rates further increase the need to identify defective products early on in the treatment process.
Given the quality control standards necessary to meet production standards and the high production rates of golf ball manufacturing plants, actions to correct a malfunction in the automated processing equipment should be taken as soon as possible to reduce the number of defective golf balls produced. The sooner a defect is detected, the lower the likelihood of reaching the predetermined number of defects initiating a need for further quality assurance corrective measures, as described above, to be taken. Accordingly, there is a need for speedy and efficient inspection of golf balls so that any manufacturing problem may be corrected almost immediately to reduce the further production of defective balls.
A variety of automated inspection systems and methods are known for use in quality control of automated processing stations, such as for coating, finishing, or otherwise affecting the surface appearance of products. For example, U.S. Pat. No. 5,665,840 to Tingey et al. discloses a method of detecting the coverage of a lubricant coating on a non-spherical article. Inspection apparatuses currently known for inspecting spherical objects generally require rotation of the object and cannot account for the three-dimensional contoured surface. For example, U.S. Pat. No. 5,703,687 to Kumagai et al. shows an automated inspection system which requires the addition of golf ball rotating equipment to the usual automated conveying equipment used to convey golf balls from an automated processing apparatus.
The spherical shape of the golf ball makes automated inspection of the three-dimensional surface difficult to achieve by the two-dimensional analysis techniques of inspection systems used in other industries. The addition of contours, in the form of dimples, on an already spherical object further complicates automated inspection thereof. Standard machine vision inspection systems using a template based inspection technique desensitized to prevent false rejections of prints or contoured surfaces are also desensitized to small defects on the edge of the print and thus are not completely effective. Prior art inspection systems have not been successful at achieving the proper combination of machine vision components, lighting, optics, and image processing techniques necessary to successfully analyze the printed images on golf balls to provide an on-line inspection system.
Thus, the golf ball manufacturing industry has heretofore relied on manual inspection to determine the quality of the various processes performed in manufacturing a golf ball. However, because the high production rate typically encountered in the industry far exceeds the speed with which manual inspection can be performed, such manual inspection cannot be performed on every ball, thus impeding efficiency, and potentially resulting in a certain number of undetected defective balls. Moreover, manual inspection is not 100% effective, given the possibility of human error or oversight, and may cause the inspected ball to be marred by the manual handling.
Thus, although automation of the golf ball manufacturing process has resulted in high production rates, such production rates are subject to the efficiency and speed with which quality inspection may be performed. If inspection is not performed routinely and quickly, a high number of defective products may be produced before appropriate measures are taken to correct the cause of the defect.